With the introduction of the Combat mechanic, there will be situations in which you will want to react to a card played by your opponent. Do Magic the Gathering stack rules apply here?

For example, my opponent plays Power and Glory to inflict 2 damage to my wounded minion with 2 health remaining and kill it. Can I play Gregor Dzanic in response to increase the health of my minion by 1 point and thus save him from dying? Or do the effects resolve immediatelly without any chance to respond?

The active player determines order of resolution. So on your turn, you have the advantage when responding to things.

If multiple players attempt to resolve a combat effect at the same time, the active player resolves 1 effect and then each player clockwise may resolve 1 effect. Repeat until all players have finished resolving effects.

Active player determines order? So if Player 1 is attacking, this could happen?

Player 1: I attack.Player 2: I play Card A, which heals my dude.Player 1: I play Card B, which damages your dude. That happens before your Card A.Player 2: Then I play Card C, which damages your attacker. Player 1: I want to play Card D, which I want to happen before your card C, but after your Card B. Order of resolution is A-B-D-C.Player 2: OK...I want to play Card E, then.Player 1: Hrmmm...new order. E-B-A-C-D.

...and so on, until everyone agrees to stop playing cards? What if the new order makes a particular card play pointless? "No takebacks?"

...and so on, until everyone agrees to stop playing cards? What if the new order makes a particular card play pointless? "No takebacks?"

You have it exactly. As active player you have the advantage should opposing effect match-ups exist in the game. Granted, in the 3+ player game you better be careful with how your choices effect the political meta-game.

I am sorry to say it, but this is just ridiculous. Too complicated and not intuitive at all. You give players a new great mechanic and than impose such cumbersome rules while at the same time limiting the effectiveness of defense/healing effects? Re-Changing the order of cards as you wish?

It should be the same as with chaining. First in, last out. The rules would be clear and cohesive. Each player starting with the active one can play a card in response to the first minion attack, once all the players pass, the ordrers are resolved in reverse order. Next the attack is resolved and damage dealt. Than the geme progresses to the next minion attack.

Double checked my playtest notes, found your answer: "if multiple players attempt to resolve a combat effect at the same time, the active player resolves 1 effect and then each player clockwise may resolve 1 effect. Repeat until all players have finished resolving effects."

I've really gotta stop answering questions when lacking sleep...

Edit: Forgot to mention that we tested first in, last out, but it doesn't work with these effects as you end up with people all yelling out their intended actions and then arguing over who said it first...

Double checked my playtest notes, found your answer: "if multiple players attempt to resolve a combat effect at the same time, the active player resolves 1 effect and then each player clockwise may resolve 1 effect. Repeat until all players have finished resolving effects."

I've really gotta stop answering questions when lacking sleep...

Edit: Forgot to mention that we tested first in, last out, but it doesn't work with these effects as you end up with people all yelling out their intended actions and then arguing over who said it first...

I do not see a problem if the first player has a chance to trigger an effect first and than the opportunity passes to the next player, and so on... you could yell as much as you want but it would not help, because the order would be obvious...

I do not see a problem if the first player has a chance to trigger an effect first and than the opportunity passes to the next player, and so on... you could yell as much as you want but it would not help, because the order would be obvious...

I do not see a problem if the first player has a chance to trigger an effect first and than the opportunity passes to the next player, and so on... you could yell as much as you want but it would not help, because the order would be obvious...

Right, this way it's simple, fair and avoids abuse.

That's how reactions are handled in Game of Thrones: TCG and it's perfect! Good ruling.